1. Field of the Invention
The present invention relates to a rewritable optical recording medium and a manufacturing method and apparatus therefor. More particularly, the present invention relates to a rewritable optical recording medium and manufacturing method and apparatus therefor in which data can be recorded by the user and illegal recording and reproduction of data are disabled.
2. Description of the Related Art
Optical recording media such as a write-once DVD-R (Digital Versatile Discxe2x80x94Recordable) and a rewritable DVD-RW (DVDxe2x80x94Re-recordable) are being put into practical use or under further development. The discs have a recording capacity of a few gigabytes (GB) and data can be recorded by the user thereon. High-volume data copying can be made with almost no loss of data quality due to the remarkable improvement in performance of the large-capacity digital optical recording media as mentioned above and a recording and reproducing apparatus.
FIG. 1 is a diagram showing a layout of a physical sector in the radial direction on the recording surface of a recorded DVD-ROM (DVDxe2x80x94Read Only Memory). Information data is recorded in an information area. A lead-in area, a data area, and a lead-out area are sequentially provided along the radial direction from a start point of the information area (i.e., start point of the physical sector).
The lead-in area includes data for reproduction of the disc such as a reference code, control data for configuring a reproduction control data signal, and the like as shown in FIG. 2. A control data area is constructed by 192 ECC (Error Correction Code) blocks. In FIG. 2, constructions of the ECC blocks in the control data area are shown by using relative sector numbers 0 to 15. Each of the contents in those ECC blocks are the same control data. In other words, 192 control data of the same contents are sequentially and repetitively recorded. The ECC block consists of 16 sectors. There is recorded in each ECC block important information regarding copy protection including physical format information, disc manufacturing information, and contents provider information. The control data regarding reproduction is recorded into the control data area in the lead-in area when the information data is recorded. When the disc is reproduced, the reproducing apparatus reads the data and executes reproduction of the recorded information data such as video data and the like on the basis of the read information.
If the data in the DVD-ROM disc is RF-copied (i.e., a read signal (RF signal) is recorded as it is by a recording circuit without being subjected to signal processing) into the rewritable DVD-RW disc and the control data is illegally falsified, an illegal DVD-RW disc which cannot be distinguished from the DVD-ROM disc (i.e., an exact or a dead copy of the DVD-ROM disc) can be produced. Since a high quality and a large capacity copy can be easily made by using the DVD-RW disc as mentioned above, development of a copy protection technique is an important subject to prevent a false or illegal copy of the recorded data such as video/audio data, a computer program, or the like.
The present invention is made in consideration of the foregoing problems and it is an object of the present invention to provide a rewritable optical recording medium which prevents illegal recording and reproduction of information data and manufacturing method and apparatus therefor.
To achieve the object, according to one aspect of the present invention, there is provided a rewritable optical recording medium on which a land track and a groove track for recording a data signal are formed, which comprises a segmented groove area in which the groove track is segmented along a rotating direction of the optical recording medium by groove non-forming portions to form a plurality of groove portions; and a continuous groove area in which a continuous groove is formed, the continuous groove having a groove width smaller than a groove width in the segmented groove area.
According to another aspect of the present invention, there is provided A method of manufacturing a master disc for a rewritable optical recording medium having a land track and a groove track for recording a data signal by irradiating a laser beam on the master disc, which comprises the steps of forming a segmented groove track having a plurality of groove portions in a first area of the optical recording medium along a rotating direction of the optical recording medium; and forming, in a second area of the optical recording medium, a continuous groove track having a groove width smaller than a groove width of the first area.